1. Field of the Invention
This invention relates a test piece for use in DNA analysis, immunological analysis and the like, a method of and an apparatus for manufacturing the test piece, and a method of and a system for reading the test piece, and more particularly to an improvement of a sequence of specific binding agents on the test piece.
2. Description of the Related Art
Recently, genetic engineering has been making rapid development and there has been progressing a human genome project for decoding a sequence of bases in human genomes which are as many as 100,000.
Further enzyme immunoassay which uses an antigen-antibody reaction, fluorescent antibody technique and the like are employed in diagnosis and/or investigation and research for DNAs which affect genetic diseases has been progressing. As a method of such research, microarray technique is greatly remarked.
As shown in FIG. 5, in the microarray technique, there is employed a microarray chip (sometimes called a DNA chip) comprising a membrane filter or a slide glass bearing thereon numbers of decoded cDNAs (a specific binding agent) applied thereto in a matrix pattern at a high density (at intervals of not larger than several hundred μm). For example, DNA (substance derived from an organism) which has been extracted from a cell of a normal person A and labelled with a fluorescent dye a and DNA which has been extracted from a cell of a sample B suffering from a genetic disease and labelled with a fluorescent dye b are pipetted onto the microarray chip to hybridize the DNAs from the normal person A and the sample B with the cDNAs on the microarray chip, and exciting light beams which respectively excite the fluorescent dyes a and b are caused to scan the cDNAs on the microarray chip. Then fluorescence emitted from the cDNAs upon excitation is detected by a photodetector and which cDNAs have been hybridized with the DNAs from the normal person A and the sample B is determined on the basis of the result of the detection of the fluorescence. The DNAs which are expressed or lost by the genetic disease are determined by comparison of cDNAs hybridized with the DNAs from the normal person A with those hybridized with the DNAs from the sample B.
As described above, the microarray chip is formed by applying an enormous number of cDNAs on a substrate such as a slide glass. When manufacturing the microarray chip, a needle-like coating chip is dipped in one of cDNAs and the cDNA adhering to the chip is spotted on the substrate in a predetermined position. Thereafter the coating chip is washed and dried, and then is dipped on another cDNA. These operations are repeated until all the cDNAs are applied to the substrate.
The number of cDNAs to be applied to the substrate sometimes reaches several hundreds of thousands and it takes a very long time to manufacture the microarray chip. Accordingly, the microarray chip is very expensive, which obstructs promoting investigation of DNA expression and/or application of immunoassay to screening.